Fuel injection valve with multiple nozzle plates

ABSTRACT

A metering assembly for a fuel injector having multiple orifice plates is disclosed. The metering assembly includes a valve body, a seat, a needle and a multi-layer orifice plate assembly. The valve body has an inlet, an outlet and a longitudinal axis extending therethrough. The seat is disposed proximate the outlet and includes a passage having a sealing surface and an orifice. The needle is reciprocally located within the housing along the longitudinal axis between a first position wherein the needle is displaced from the seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the seat, precluding fuel flow past the needle. The multi-layer orifice plate assembly is located at the housing outlet and includes a first orifice plate having a plurality of first openings extending therethrough. The orifice plate assembly further includes a second orifice plate having a plurality of second openings extending therethrough. The plurality of first openings and the plurality of second openings are fluidly connected by at least one channel. A method of accelerating fuel through the injector is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/159,229, filed Oct. 13, 1999.

FIELD OF THE INVENTION

The invention relates to fuel injectors, and more particularly, to fuelinjectors having multiple interchangeable nozzle plates.

BACKGROUND OF THE INVENTION

Fuel injectors are commonly employed in internal combustion engines toprovide precise metering of fuel into each combustion chamber.Additionally, each fuel injector atomizes the fuel during injection intothe respective combustion chamber, breaking the fuel into a large numberof very small particles, increasing the surface area of the fuel beinginjected and allowing the oxidizer, typically ambient air, to morethoroughly mix with the fuel prior to combustion. The precise meteringand atomization of the fuel reduces combustion emissions and increasesthe fuel efficiency of the engine.

An electromagnetic fuel injector typically utilizes a solenoid assemblyto supply an actuating force to a fuel metering valve. Typically, thefuel metering valve is a plunger style needle valve which reciprocatesbetween a closed position, when the needle is seated in a seat toprevent fuel from escaping through a metering orifice into thecombustion chamber, and an open position, where the needle is liftedfrom the seat, allowing fuel to discharge through the metering orificeand into the combustion chamber.

Typically, fuel injectors employ a metering nozzle or orifice comprisedof a single orifice plate with a plurality of orifice openings extendingtherethrough through which pressurized fuel is introduced into thecombustion chamber. Modifications to these metering orifices includemultiple orifice plates stacked upon each other to provide alternatepathways for the fuel immediately prior to injection into the combustionchamber. These alternate pathways increase the turbulence of the fuelflow, providing greater atomization of the fuel as the fuel passesthrough the orifice openings, providing for enhanced mixture of the fuelwith combustion air which reduces unwanted exhaust emissions andimproves the fuel efficiency of the engine.

Typically, injectors with multiple orifice plates include a first toporifice plate having a plurality of openings extending therethrough, abottom orifice plate having a like plurality of openings extendingtherethrough, and an open space between the top orifice plate and thebottom orifice plate for redirecting the fuel flow between the outlet ofthe top orifice plate orifice openings and the inlet of the bottomorifice plate orifice openings. Additionally, the space between the topand bottom orifice plates generally includes walls or other obstructionswhich tend to direct the fuel from the outlet of the top orifice plateto a particular orifice opening in the bottom orifice plate, creating arelatively laminar flow and precluding a fuel stream from one toporifice plate orifice opening from impinging into the stream fromanother top orifice plate orifice opening. Additionally, fuel injectorswith multiple orifice plates require the orifice plates to be fused orelectroplated together, precluding the ability to interchange orificeplates to obtain different fuel flow patterns.

It would be beneficial to develop a fuel injector having a meteringorifice with multiple orifice plates which includes a fully open spacebetween top and bottom orifice plates and which also allowsinterchangeability of different orifice plates to produce different flowstream patterns.

SUMMARY OF THE INVENTION

Briefly, the present invention provides a fuel injector comprising ahousing, a seat, a needle, and a multi-layer orifice plate assembly. Thehousing has an inlet, an outlet and a longitudinal axis extendingtherethrough. The seat is disposed proximate the outlet and includes asealing surface and a passage extending therethrough. The needle isreciprocally located within the housing along the longitudinal axisbetween a first position wherein the needle is displaced from the seat,allowing fuel flow past the needle, and a second position wherein theneedle is biased against the seat, precluding fuel flow past the needle.The multi-layer orifice plate assembly is located at the housing outlet.The orifice plate assembly includes a first orifice plate having aplurality of first openings extending therethrough. The orifice plateassembly also includes a second orifice plate having a plurality ofsecond openings extending therethrough. The plurality of first openingsand the plurality of second openings are fluidly connected by at leastone channel.

The present invention also provides a fuel injector comprising ahousing, a seat, a needle and a multi-layer orifice plate assembly. Thehousing has an inlet, an outlet and a longitudinal axis extendingtherethrough. The seat is disposed proximate the outlet and includes asealing surface and a passage extending therethrough. The needle isreciprocally located within the housing along the longitudinal axisbetween a first position wherein the needle is displaced from the seat,allowing fuel flow past the needle, and a second position wherein theneedle is biased against the seat, precluding fuel flow past the needle.The multi-layer orifice plate assembly is located at the housing outletand includes a first orifice plate having a plurality of first openingsextending therethrough. The plurality of first openings are each spaceda first predetermined radial distance from the longitudinal axis. Theorifice plate assembly further includes a second orifice plate having aplurality of second openings extending therethrough. The plurality ofsecond openings are each spaced a second predetermined radial distancefrom the longitudinal axis such that the second predetermined radialdistance is less than the first predetermined radial distance. Theorifice plate assembly further includes a third orifice plate locatedbetween the first orifice plate and the second orifice plate. The thirdorifice plate includes a third orifice plate central opening extendingtherethrough along the longitudinal axis such that the third orificeplate central opening fluidly connects the plurality of first orificeplate openings and the plurality of second orifice plate openings.

The present invention also provides a method of accelerating a velocityof fuel through a fuel injector having a longitudinal axis and amulti-layer orifice plate. The method comprises the steps of directingthe fuel through openings in a top orifice plate; directing the fuelinto a space between the top orifice plate and a bottom orifice plate;and directing the fuel through openings in the bottom orifice plate, theopenings in the bottom orifice plate being radially closer to thelongitudinal axis than the openings in the top orifice plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate the presently preferredembodiments of the invention, and, together with the general descriptiongiven above and the detailed description given below, serve to explainfeatures of the invention. In the drawings:

FIG. 1 is a side view, in section, of a discharge end of a fuel injectorof the present invention incorporating a multiple orifice plateconfiguration according to a first embodiment of the present invention,with a needle in a closed position;

FIG. 2 is an enlarged view of the discharge end of the needle of FIG. 1,with the needle in an open position;

FIG. 3 is a top plan view of a top orifice plate according to the firstpreferred embodiment of the present invention;

FIG. 4 is a top plan view of a bottom orifice plate of the presentinvention;

FIG. 5 is a top plan view of a spacer orifice plate of the presentinvention;

FIG. 6 is an enlarged view of the discharge end of the fuel injectorincorporating a multiple orifice plate configuration according to asecond embodiment of the present invention; and

FIG. 7 is a top plan view of a top orifice plate according to the secondpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, like numerals are used to indicate like elementsthroughout. A first preferred embodiment, shown in FIGS. 1 and 2, is afuel metering assembly 10 for use in a fuel injection system of aninternal combustion engine. The metering assembly 10 includes a valvebody 20, a seat 30, a needle 40, and a generally planar composite nozzleor orifice plate assembly 50. Details of the operation of the fuelmetering assembly 10 in relation to the operation of the internalcombustion engine (not shown) are well known and will not be describedin detail herein, except as the operation relates to the preferredembodiments. Although the preferred embodiments are generally directedto injector valves for internal combustion engines, those skilled in theart will recognize from present disclosure that the preferredembodiments can be adapted for other applications in which precisemetering of fluids is desired or required.

The valve body 20 has an upstream or inlet end 210 and a downstream oroutlet end 220. The valve body 20 includes an armature 240 as shown inFIG. 1. The words “upstream” and “downstream” designate flow directionsin the drawings to which reference is made. The upstream side is towardthe top of each drawing and the downstream side is toward the bottom ofeach drawing. The needle 40 is connected to the armature 240. Anelectromagnetic coil (not shown) located above the valve body 20 isselectively energized and deenergized to reciprocate the armature 240and the needle 40 within the valve body 20. The valve body 20 furtherincludes a body 260 which includes a housing chamber 262. The housingchamber 262 extends through a central longitudinal portion of the valvebody 20 along a longitudinal axis 270 extending therethrough and isformed by an interior housing wall 264. A needle guide 280 having acentral needle guide opening 281 and a plurality of radially spaced fuelflow openings 282 is located within the housing chamber 262 proximate tothe downstream end 220 of the valve body 20. The needle guide assists inmaintaining reciprocation of the needle 40 along the longitudinal axis270.

The seat 30 is located within the housing chamber 262 proximate to theoutlet end 220 between the needle guide 280 and the discharge ends 220.The seat 30 includes a passage or orifice 320 which extends through theseat 30 generally along the longitudinal axis 270 of the valve body 20and is formed by a generally cylindrical wall 322. Preferably, a center321 of the orifice 320 is on the longitudinal axis 270. The seat 30 alsoincludes an annularly shaped beveled sealing surface 330 which surroundsthe orifice 320 and tapers radially downward and inward toward theorifice 320 such that the sealing surface 330 is oblique to thelongitudinal axis 270. The words “inward”, “outward”, and derivativesthereof refer to directions toward and away from, respectively, thelongitudinal axis.

The needle 40 is connected to the armature 240 and is reciprocallylocated within the housing chamber 262 generally along the longitudinalaxis 270 of the valve body 20. The needle 40 is reciprocable between afirst, or open, position wherein the needle 40 is displaced from theseat 30 (as shown in FIG. 2), allowing pressurized fuel to flowdownstream past the needle 40, and a second, or closed, position whereinthe needle 40 is biased against the seat 30 (as shown in FIG. 1) by abiasing element (not shown), preferably a spring, precluding fuel flowpast the needle 40.

The needle 40 includes a first portion 410 which has a firstcross-sectional area A1 and a second portion 420 which has a secondcross-sectional area A2. The second portion 420 includes a generallyspherical contact face 422 (shown in FIG. 6) which sealingly engages thebeveled sealing surface 330 when the needle 40 is in the closedposition. However, those skilled in the art will recognize that agenerally flat or planar end face 426 (shown in FIG. 2) can be locatedat the downstream tip of the needle 40. The end face 426 is preferablygenerally perpendicular to the longitudinal axis 270 of the valve body20. A generally annular area of contact 423 provides a solid sealbetween the needle 40 and the seat 30 and reduces the possibility offuel leakage past the needle 40.

Preferably, both the first and second cross-sectional areas A1, A2 arecircular, although those skilled in the art will recognize that thefirst and second cross-sectional areas A1, A2 can be other shapes aswell. This configuration reduces the mass of the needle 40 whileretaining a relatively large sealing diameter of the contact face 422 soas to provide a relatively generous sealing area of the needle 40 forengagement of the contact face 422 when the needle 40 is in the closedposition. The increased cross-sectional area A2 of the needle provides alarger guide surface relative to the mean needle diameter, therebyimproving the wear resistance of the internal surface of the centralneedle guide opening 281. The improved wear resistance of the internalsurface of the central needle guide opening 281 is due to reducedloading compared to that of a conventional base guide diameter which wasused with prior art needles of a generally constant cross-sectionalarea. For example, a typical prior art needle will have a substantiallycontinuous cylindrically shaped shaft which terminates at an end portionwherein the cross-sectional area at the top portion of the needle may betwice as much as the cross-sectional area A1 of the needle 40 shown inFIG. 1. The second cross-sectional area A2 is sized so that the secondportion 420 extends through the central needle guide opening 281 with agap of approximately 10-15 microns between the needle 40 and the plate280.

The needle 40 is reciprocable between the closed position (shown inFIG. 1) and the open position (shown in FIG. 2). When the needle 40 isin the open position, a generally annular channel 430 extending towardthe longitudinal axis 270 is formed between the contact face 422 and thesealing surface 330.

Referring to FIG. 2, the orifice plate assembly 50 is a multi-layercomposite orifice plate which is constructed from at least two separateorifice plates, a top orifice plate 510 and a bottom orifice plate 520and is located at the housing outlet 220. A spacer orifice plate 530,located between the top orifice plate 510 and the bottom orifice plate520, is preferably used. However, the spacer orifice plate 530 can beomitted as long as a predetermined gap is maintained between adownstream face 514 of the top orifice plate 510 and an upstream face522 of the bottom orifice plate 520.

A first embodiment of the orifice plate assembly 50, shown in FIG. 2,includes the top orifice plate 510 having an upstream face 512, thedownstream face 514, and a plurality of generally arcuate holes oropenings 516 extending through the top orifice plate 510 and radiallyspaced a first predetermined distance from the longitudinal axis 270.The arcuate openings 516 are preferably symmetrically spaced from thelongitudinal axis 270 and approximate a circular shape as shown in FIG.3. Preferably, three arcuate openings 516 are preferred, although thoseskilled in the art will recognize that more or less than three arcuateopenings 516 can be used. Preferably, a relatively large total surfacearea of the arcuate openings 516 is preferred to reduce pressure lossthrough the arcuate openings 516. However, those skilled in the art willrecognize that a total surface area of the arcuate openings 516 shouldnot be so great as to degrade the strength of the top orifice plate 510.The top orifice plate 510 is preferably generally perpendicular to thelongitudinal axis 270. Preferably, the plurality of arcuate openings 516are immediately downstream and adjacent to the seat orifice 320, asshown in FIG. 2.

The bottom orifice plate 520 has the upstream face 522, a downstreamface 524, and a plurality of preferably circular or polygonal meteringholes or openings 526 extending through the bottom orifice plate 520 andradially spaced a second predetermined distance from the longitudinalaxis 270. The openings 526 are preferably symmetrically spaced from thelongitudinal axis 270 and approximate a circular shape as shown in FIG.4. One advantage of a polygonal opening is that the corners between thesides of the opening can be finely tuned to control fuel targeting intothe combustion chamber. The metering openings 526 are preferablysymmetrically spaced a different distance from the longitudinal axis 270than the arcuate openings 516 and approximate a generally circular shapeas shown in FIG. 4, such that the top orifice plate arcuate openings 516and the bottom orifice plate metering openings 526 do not overlap eachother, as seen in FIG. 2.

Preferably, the bottom orifice plate openings 526 are closer to thelongitudinal axis 270 than the top orifice plate openings 516, althoughthose skilled in the art will recognize that the bottom orifice plateopenings 526 can be farther from the longitudinal axis 270 than the toporifice plate openings 516. Preferably, eight metering openings 526 arepreferred, although those skilled in the art will recognize that more orless than eight metering openings 526 can be used. However, it isimportant to note that the number of arcuate openings 516 cannot equalthe number of metering openings 526. The bottom orifice plate 520 ispreferably generally perpendicular to the longitudinal axis 270.

The spacer orifice plate 530, shown in FIG. 5, between the top andbottom orifice plates 510, 520, is used to control vertical spacingbetween the top and bottom orifice plates 510, 520 so that an optimizedradial fuel velocity component can be generated and maintained. As shownin FIGS. 2 and 5, the spacer orifice plate 530 includes an upstream face532, a downstream face 534, and a generally channel or circular opening536 which extends radially from the longitudinal axis 270. The opening536 is in fluid communication with each of the plurality of arcuateopenings 516 and the plurality of metering openings 526 so that the fuelcan flow from the arcuate openings 516, through the circular opening536, and through the metering openings 526.

A virtual extension 340 of the seat 30 can be projected onto theupstream face 512 of the top orifice plate 510 so as to intercept theupstream face 512 of the top orifice plate 510 at a point “A”, shown inFIG. 2. The virtual extension 340 can be further projected onto theupstream face 522 of the bottom orifice plate 520 so as to intercept theupstream face 522 of the bottom orifice plate 520 at a point “B”, shownin FIG. 2. Referring to FIG. 3, the arcuate openings 516 aresufficiently far from the longitudinal axis 270 such that a virtualcircle 518 formed by the virtual extension 340 of the seat 30 onto theupstream face 512 of the top orifice plate 510 at “A” has a smallerdiameter than a virtual circle 519 drawn around an outer perimeter ofthe arcuate openings 516. Similarly, referring to FIG. 4, the meteringopenings 526 are sufficiently far from the longitudinal axis 270 suchthat a virtual circle 528 formed by the virtual extension 340 of theseat 30 onto the upstream face 522 of the bottom orifice plate 520 at“B” has a smaller diameter than a virtual circle 529 drawn around anouter perimeter of the metering openings 526. This ensures that the flowof fuel between the arcuate openings 516 and the metering openings 526when the needle 40 is in the open position directs the fuel onto theupstream face 522 of the bottom orifice plate 520 to provide atransverse flow of the fuel across the upstream face 522 of the bottomorifice plate 520 to the metering openings 526 prior to the fuelentering the metering openings 526.

The top orifice plate 510 eliminates any effect of the movement of theneedle 40 relative to the seat 30 on the spray definition and reduces oreliminates flow instability of the fuel prior to entering the bottomorifice plate openings 526. The bottom orifice plate 520 is the primarymetering orifice plate through which the fuel passes immediately priorto entering the combustion chamber. The space between the downstreamface 514 of the top orifice plate 510 and the upstream face 522 of thebottom orifice plate 520 is preferably between 75 microns and 300microns.

The use of the three distinct orifice plates, the top orifice plate 510,the bottom orifice plate 520, and the spacer orifice plate 530 allowsfor a significant level of flexibility in manufacturing the meteringassembly 10. Different configurations of the top, bottom, and spacerplates 510, 520, 530 are removable from and replaceable with other top,bottom, and spacer plates (not shown) and can be mixed and matched tocreate optimum flow paths for turbulence enhanced atomization and fueltargeting. Fuel flow characteristics can be tailored to the applicationrequired without any changes in the product fabrication process.

Additionally, although not shown, a fourth orifice plate, similar spacerorifice plate 530 can be inserted between the upstream face 512 of thetop orifice plate 510 and the downstream end of the valve seat 30. Sucha configuration can be used if the orifice 320 is not large enough toprovide desired radial spacing of the openings 516 in the top orificeplate 510 from the longitudinal axis 270.

Preferably, the plates are fabricated by the type of process that isconsistent with the geometric requirements for that portion of the fuelpath. Preferably, the top orifice plate 510 and the spacer orifice plate530 can easily be fabricated by an inexpensive process such as punchingor etching. Preferably, the more critical metering openings 526 in thebottom orifice plate 520 would be processed by a precision punching orprecision laser machine process to provide the precise dimensionsrequired for required targeting into the combustion chamber.

Although three orifice plates 510, 520, 530 are preferred, those skilledin the art will recognize that the spacer orifice plate 530 can becombined with one of the top or bottom orifice plates 510, 520 usingmanufacturing processes which are well known to those skilled in theart, resulting in only two orifice plates. Additionally, the orificeplates 510, 520, 530 can be dimpled together to generate a variety ofspray patterns. The fuel flow rate is controlled by the location and thesize of the metering openings 526 in the bottom orifice plate 520. Themetering openings 526 are distributed so that the turbulence intensityis equal and maximized for each individual metering opening 526 in thebottom orifice plate 520.

Preferably, the orifice plates 510, 520, 530 are constructed from ametallic material, and more preferably from stainless steel, althoughthose skilled in the art will recognize that at least one of the orificeplates 510, 520, 530 can be constructed from other suitable materials.

The operation of the fuel metering assembly 10 is as follows.Pressurized fuel flow into the metering assembly 10 is provided by afuel pump (not shown). The pressurized fuel enters the metering assembly10 and passes through a fuel filter (not shown) to the armature 240, andto the housing chamber 262. The fuel flows through the housing chamber262, the fuel flow openings 282 in the guide 280 to the interfacebetween the contact face 422 and the sealing surface 330. In the closedposition (shown in FIG. 1), the needle 40 is biased against the seat 30so that the contact face 422 sealingly engages the sealing surface 330,preventing flow of fuel through the composite orifice plate assembly 50.

In the open position, shown in FIG. 2, a solenoid or other actuatingdevice, (not shown) reciprocates the needle 40 to an open position,removing the contact face 422 of the needle 40 from the sealing surface330 of the seat 30 and forming the generally annular channel 430.Pressurized fuel within the housing chamber 262 flows past the generallyannular channel 430 formed by the needle 40 and the seat 30 and impingeson the upstream face 512 of the top orifice plate 510. The fuel thenflows through the plurality of arcuate openings 516 into the open space536 in the spacer orifice plate 530 between the top and bottom orificeplates 510, 520. The fuel then accelerates along the upstream face 522of the bottom orifice plate 520 in a transverse direction relative tothe metering openings 526. The fuel then flows across the meteringopenings 526 where the fuel is atomized as it passes through themetering openings 526 into the combustion chamber. Fuel flows into thespace bounded by the downstream face 514 of the top orifice plate 510and the upstream face 522 of the bottom orifice plate 520. Additionalturbulence is generated to enhance the fuel atomization as the fuelpasses through the metering openings 526.

An alternate embodiment includes a modified top orifice plate 550 shownin FIGS. 6 and 7. Although similar to the top orifice plate 510 in FIGS.1, 2 and 3, the top orifice plate 550 includes an upstream face 552, adownstream face 554, and a plurality of arcuate openings 556. The toporifice plate 550, however, is modified to include an additional centralhole or opening 558 which extends through the top orifice plate 550 andextends radially from the longitudinal axis 270. The central opening 558is fluidly connected to the plurality of metering openings 526 by way ofthe central opening 536 in the spacer plate 530. The central opening 558increases the opening surface area in the top orifice plate 550 andreduces fuel pressure loss between the top and bottom orifice plates550, 520. Additionally, the central opening 558 generates and controlsimpinging fuel flow streams “F” as shown in FIG. 6. These impingingstreams “F” generate additional turbulence in the fuel to promote fuelatomization.

Preferably, in each of the embodiments described above, the seat 30 isconstructed from stainless steel and the needle 40 is constructed fromstainless steel. However, those skilled in the art will recognize thatthe seat 30 and the needle 40 can be constructed of other, suitablematerials.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined in the appended claims.

What is claimed is:
 1. A fuel injector comprising: a housing having aninlet, an outlet and a longitudinal axis extending therethrough; a seatdisposed proximate to the outlet, the seat including a sealing surfaceand a passage extending therethrough; a needle being reciprocallylocated within the housing along the longitudinal axis between a firstposition wherein the needle is displaced from the seat, allowing fuelflow past the needle, and a second position wherein the needle is biasedagainst the seat, precluding fuel flow past the needle; and amulti-layer orifice plate assembly located at the housing outlet, theorifice plate assembly including: a first orifice plate having at leasta plurality of first openings, each first opening being generallyarcuate and spaced about the longitudinal axis at a first predeterminedradial distance from the longitudinal axis; and a second orifice plateseparate from the first orifice plate such that the first plate islocated between the seat and a second orifice plate, the second orificeplate having a plurality of second openings extending therethrough, eachsecond opening being spaced a second predetermined radial distance fromthe longitudinal axis, the plurality of first openings and the pluralityof second openings being fluidly connected by at least one channel. 2.The fuel injector according to claim 1, wherein the second predeterminedradial distance is less than the first predetermined radial distance. 3.The fuel injector according to claim 1, wherein the first orifice platefurther includes a central opening extending therethrough along thelongitudinal axis, the central opening being fluidly connected to theplurality of second openings.
 4. The fuel injector according to claim 1,further including a third orifice plate located between the firstorifice plate and the second orifice plate, the third orifice plateincluding a third orifice plate central opening extending therethroughalong the longitudinal axis, the third orifice plate central openingfluidly connecting the plurality of first orifice plate openings and theplurality of second orifice plate openings.
 5. The fuel injectoraccording to claim 4, wherein at least one of the first orifice plate,the second orifice plate and the third orifice plate are removable fromand replaceable with at least a fourth orifice plate.
 6. The fuelinjector according to claim 1, wherein the second orifice plate openingsare non-circular.
 7. The fuel injector according to claim 1, wherein theneedle has a generally spherical end face.
 8. The fuel injectoraccording to claim 7, wherein a plane of each of the first and secondorifice plates is generally perpendicular to the longitudinal axis. 9.The fuel injector according to claim 1, wherein at least one of thefirst and second orifice plates is constructed from a metal.
 10. A fuelinjector comprising: a housing having an inlet, an outlet and alongitudinal axis extending therethrough; a seat disposed proximate theoutlet, the seat including a sealing surface and a passage extendingtherethrough; a needle being reciprocally located within the housingalong the longitudinal axis between a first position wherein the needleis displaced from the seat, allowing fuel flow past the needle, and asecond position wherein the needle is biased against the seat precludingfuel flow past the needle; and a multi-layer orifice plate assemblylocated at the housing outlet, the orifice plate assembly including: afirst orifice plate having at least a plurality of first openings, eachfirst opening being generally arcuate and spaced about the longitudinalaxis at a first predetermined radial distance from the longitudinalaxis; a second orifice plate separate from the first orifice plate suchthat the first plate is located between the seat and a second orificeplate, the second orifice plate having a plurality of second openingsextending therethrough, each second opening being spaced a secondpredetermined radial distance from the longitudinal axis, the secondpredetermined radial distance being less than the first predeterminedradial distance; and a third orifice plate located between the firstorifice plate and the second orifice plate, the third orifice platebeing separate from the first and second orifice plates, the thirdorifice plate including a third orifice plate central opening extendingtherethrough along the longitudinal axis, the third orifice platecentral opening fluidly connecting the plurality of first and secondopenings.
 11. The fuel injector according to claim 10, wherein the firstorifice plate further includes a central opening extending therethroughalong the longitudinal axis, the central opening being fluidly connectedto the plurality of second openings.
 12. The fuel injector according toclaim 10, wherein at least one of the first orifice plate, the secondorifice plate and the third orifice plate are removable from andreplaceable with at least a fourth orifice plate.
 13. The fuel injectoraccording to claim 10, wherein the second predetermined radial distanceis less than the first predetermined radial distance.
 14. The fuelinjector according to claim 10, wherein the second orifice plateopenings are non-circular.
 15. The fuel injector according to claim 10,wherein a plane of each of the first and second orifice plates isgenerally perpendicular to the longitudinal axis.
 16. The fuel injectoraccording to claim 10, wherein at least one of the first, second, andthird orifice plates is constructed from a metal.
 17. A method ofaccelerating a velocity of fuel through a fuel injector having alongitudinal axis and a multi-layer orifice plate assembly disposedproximate a valve seat, the method comprising: directing the fuelthrough openings in a top orifice plate disposed between the valve seatand a bottom orifice plate, the openings in the top orifice plate beinggenerally arcuate with respect to the longitudinal axis; directing thefuel into a space between the top orifice plate and a bottom orificeplate; and directing the fuel through openings in the bottom orificeplate, the openings in the bottom orifice plate being closer to thelongitudinal axis than the openings in the top orifice plate.
 18. Themethod according to claim 17, further comprising the step of providing aspacer orifice plate between the top orifice plate and the bottomorifice plate, the spacer orifice plate having an opening in fluidcommunication with the openings in the top orifice plate and theopenings in the bottom orifice plate.
 19. The method according to claim17, wherein the openings in the bottom orifice plate define a generallyradial pattern about the longitudinal axis.
 20. A fuel injectorcomprising: a housing having an inlet, an outlet and a longitudinal axisextending therethrough; a seat disposed proximate to the outlet, theseat including a sealing surface and a passage extending therethrough; aneedle being reciprocally located within the housing along thelongitudinal axis between a first position wherein the needle isdisplaced from the seat, allowing fuel flow past the needle, and asecond position wherein the needle is biased against the seat,precluding fuel flow past the needle; a multi-layer orifice plateassembly located at the housing outlet, the orifice plate assemblyincluding: a first orifice plate having at least a plurality of firstopenings extending therethrough; and a second orifice plate separatefrom the first orifice plate, the second orifice plate having aplurality of second openings extending therethrough each being spaced asecond predetermined radial distance from the longitudinal axis, theplurality of first openings and the plurality of second openings beingfluidly connected by at least one channel; and a virtual extensionsealing surface forming a virtual circle on the first and second platessuch that the plurality of the first openings are outside the virtualcircle on the first plate and the plurality of the second openings areoutside the virtual circle on the second plate.
 21. A fuel injectorcomprising: a housing having an inlet, an outlet and a longitudinal axisextending therethrough; a seat disposed proximate the outlet, the seatincluding a sealing surface and a passage extending therethrough; aneedle being reciprocally located within the housing along thelongitudinal axis between a first position wherein the needle isdisplaced from the seat, allowing fuel flow past the needle, and asecond position wherein the needle is biased against the seat precludingflow past the needle; a multi-layer orifice plate assembly located atthe housing outlet, the orifice plate assembly including: a firstorifice plate having at least a plurality of first openings extendingtherethrough, the plurality of first openings each being spaced a firstpredetermined radial distance from the longitudinal axis; a secondorifice plate separate from the first orifice plate, the second orificeplate having a plurality of second openings extending therethrough eachbeing spaced a second predetermined radial distance from thelongitudinal axis, the second predetermined radial distance being lessthan the first predetermined radial distance, the plurality of firstopenings and the plurality of second openings being fluidly connected byat least one channel; and a third orifice plate located between thefirst orifice plate and the second orifice plate, the third orificeplate being separate from the first and second orifice plates, the thirdorifice plate including a third orifice plate central opening extendingtherethrough along the longitudinal axis, the third orifice platecentral opening fluidly connecting the plurality of first and secondopenings; and a virtual extension of the sealing surface forming avirtual circle on the first and second plates such that the plurality ofthe first openings are outside the virtual circle on the first plate andthe plurality of the second openings are outside the virtual circle onthe second plate.
 22. The fuel injector of claim 21, wherein the arcuateopenings are located outside the virtual circle and the central openingis located within the virtual circle.